This invention relates to an apparatus and method for supplying alternating current power to electrical devices, and more particularly, to an apparatus and method which allows for setting predetermined electrical devices for either an automatic or manual change from electric utility power to battery power during a power outage.
Various types of backup power supply systems are known which provide backup battery power to sump pumps, refrigerators, computers, heating equipment and other types of electric devices.
These devices do not provide the capability to select specific electrical devices for either an immediate or manual switch to battery power in the event of a power outage. In other words, the known devices cannot be set to supply power only to selected electrical devices so as to avoid overload of the battery.
An additional disadvantage of some of the known devices is that they are not connectable to power generating devices which can prevent battery burn out by charging the battery during a loss of main power.
Further, a disadvantage of known 12 volt auxiliary power systems is that a high current is needed to supply a substantial amount of power to the electrical devices. A high current flow through battery cables causes energy loss and, as a result, these 12 volt systems do not make the most efficient use of the stored battery power.
It is therefore an object of the present invention to provide an apparatus and method for supplying alternating current power to electrical devices such as sump pumps, refrigerators, computers, heating equipment and the like, which will, in the event of a power outage, automatically switch only predetermined electrical devices to battery power, with the remaining electrical devices switching to battery power only upon manual operation by a user.
It is an additional object of the present invention to provide a method and apparatus for supplying alternating current power to electrical devices wherein the battery is charged by a backup power generating device during a loss of main power.
The foregoing objects are achieved and the disadvantages of the known power supply devices are overcome by providing an apparatus which supplies alternating current power to electrical devices from an electric utility power supply or, when the utility power supply is not available, from a battery. The apparatus includes an inverter connected to the battery at a direct current input portion of the inverter. The inverter changes direct current power to alternating current power and outputs the alternating current power at its output portion.
The apparatus also includes a conversion relay connected to the utility power supply and the output portion of the inverter. The conversion relay supplies power from either the utility power supply or the battery via the inverter to the electrical devices connected to a final output portion. The final output portion includes a plurality of AC receptacles to receive plugs from electrical devices.
A charging system, such as a pulsed charging system, is connected to the utility power supply via the conversion relay and to the battery so as to enable charging of the battery with power from the utility power supply. At least one charge controller can be connected to the charging system and to a power generating device, such as a wind turbine, a solar array or the like, to charge the battery with power supplied from the power generating device.
The device includes a power converter, such as a twin inversion power unit, a triple (for 3-phase systems) inversion power unit, or a step-up transformer, that connects to a subpanel. The step-up transformer increases an input voltage from 110 volts to 220 volts to accommodate the electric devices with higher voltage requirements, such as well-pumps or the like. An inversion power unit may be used in place of a step-up transformer when, for example, the input voltage is already 220 volts.
The subpanel consists of a plurality of switches which correspond to predetermined electrical devices connected to the apparatus. Some of the subpanel switches are set in the xe2x80x9conxe2x80x9d position to effectuate automatic load pick up by the battery in the event of power outage. Therefore, when the utility power supply is unavailable, the electrical devices which correspond to the switches set in the xe2x80x9conxe2x80x9d position are supplied with power from the battery.
The electrical devices corresponding to the subpanel switches set to the xe2x80x9coffxe2x80x9d position will not receive power during a power outage unless the switches are turned to the xe2x80x9conxe2x80x9d position. Limiting the power supply to the devices corresponding to the activated switches prevents overload of the battery, as well as providing a means by which reserve capacity of the system may be maintained.
A device which filters incoming power and protects electronic equipment from damage due to distorted utility voltage caused by an energy crisis situation, such as a line conditioner, can be connected to the power converter and between the inverter and final output portion. A line conditioner may be necessary when one of the electrical devices is, for example, a computer. Additionally, the device can include a fan positioned therein to maintain a cool temperature.
In order to ensure an adequate supply of battery power during a power outage, a battery may be linked to a second cell bank. In addition, to further charge the battery, any number of charge controllers included the apparatus can be connected to the power generating devices described above.
A method for supplying alternating current power to the electrical devices from the electric utility power supply or from a battery when the utility power supply is unavailable, includes the steps of connecting the inverter to the battery at the direct current input portion of the inverter; changing direct current power to alternating current power; outputting the alternating current power at the output portion of the inverter; connecting a conversion relay to the utility power supply and to the output portion of the inverter; supplying power from either the utility power supply or the battery via the inverter to electrical devices connected at the final output portion of the apparatus; connecting the charging system to the utility power supply via the conversion relay and to the battery source; charging the battery source with power from the utility power supply; connecting the power converter to the subpanel having the plurality of switches; assigning each one of the switches to an electrical device; setting a first group of the switches to the xe2x80x9conxe2x80x9d position to cause automatic load pick up by the battery when the utility power supply is unavailable; and setting a second group of the switches to the xe2x80x9coffxe2x80x9d position to cause manual load pick up by the battery when the utility power supply is unavailable.
The method may also include the steps of connecting at least one charge controller to the charging system and a power generating device; and charging the battery with power supplied from the power generating device.